1. Field of the Invention
This invention relates to an electric component such as an IC component mounted on a printed circuit board of surface-mounting system.
2. Description of the Prior Art
The surface-mounting system, unlike a conventional insertion system, in which leads of electric components are inserted through through holes formed in a printed circuit board, is one, in which leads of electric components are electrically connected by soldering them to a connection land pattern formed on a printed circuit board, and which has been extensively utilized with automatization of mounting of electric components.
FIGS. 8 and 9 are perspective views showing prior art IC components used in the surface-mounting system.
In the Figures, reference numeral 1 designates an IC package, from the opposite sides of which a plurality of leads 2 are led out toward a printed circuit board (not shown). Each lead 2 has an outwardly (FIG. 8) or inwardly (FIG. 9) horizontally bent end portion, which constitutes a bonding portion 2a to be soldered to a corresponding connection land 3 formed on a printed circuit board.
The IC component having the above construction is set on a printed circuit board with the bonding portions 2a of the leads 2 registered to lands 3 which have been printed using a cream solder, and it is then mounted on the printed circuit board with soldering of the bonding portions 2a to the lands 3 with the solder fused in a re-flow furnace utilizing infrared rays.
In the prior art electric component the bonding portion 2a is formed by merely bending the lead 2 as described before. However, the control of the solder film thickness at the time of the cream solder printing is considerably difficult, and if insufficient solder film thickness results from insufficient amount of solder, it frequently leads to defective or unsatisfactory soldering, i.e., failure of perfect connection between the solder and lead.